On 4 November 1824 in Vienna he married Sophie of
Bavaria, a daughter of King Maximilian I of
Bavaria by his second wife Karoline of
Baden. Franz Karl was an unambitious and generally ineffectual
man, although he was a member of the Council that ruled in the
stead of his mentally retarded brother Emperor Ferdinand from 1835 to
1848. At the urging of his wife, he renounced his claims to the
throne at the time of his brother's abdication in December 1848,
allowing their eldest son Franz Joseph to take the throne. Archduke
Franz Karl died in Vienna in 1878, six years after the death of his
wife.